The invention relates to a roof edging system comprising a first section provided with a web portion to be fastened parallel to the vertical roof edge and a first rib extending transversely thereto.
Roof edging systems of the above kind are known in itself and are used for finishing the edges of a flat roof covered by a first layer of roof covering material, which also covers the gravel stop with thereon a second layer of this material which reaches halfway to the gravel stop. According to the prior art the section rests on the gravel stop and a flexible strip of web material which is then adhered to the first rib of the section and the covering layer.
The abovementioned way of finishing has many drawbacks. As a result of the great thermal expansion of the aluminum section a space of several milimeters must be preserved between two adjacent sections which must be bridged by the web material that is glued with a bitumen compound to the aluminum sections. This is, however, a time consuming and difficult operation-which can only be effected under favorable weather conditions-as a good interconnection must be made between two materials with quite different coefficients of expansion and said connection must be retained at temperatures which vary from minus 20.degree. C. to +30.degree. c. When the adherence is lost--which mostly happens unnoticed--moisture penetrates between the layers of roof covering with destructive consequences when the frost sets in: the layers of roof covering become loose and a strong wind can blow them away. The necessary space between two adjacent section parts frequently results into rupture of the roof covering; moisture which is blown along the section results into moisture stains on the brickwork, discoloring and the growth of moss.
Although the above way of finishing roofs is used extensively the problems therewith are so serious that an improvement is badly needed.
The invention offers such an improvement in the roof edging system. According to the invention the first rib therefore rests upon the roof covering layer and the section supports a second, easily dismountable and staggered section which has a cover strip laying above the first rib.
According to the invention the function of the separate strip of web material, is taken over by the cover strip of the second section. The layers of roof covering are pressed watertight against the underground by the rib of the first section and are also protected against damaging thereby; penetration of moisture is prevented by the cover strip which lies thereabove.
There is not only an important saving of costs--the investment is made only once--but another advantage is that directly after two adjacent sections have been put into place they can be covered by a second section so that the roof covering has its watertight finish.
An easy fastening of the second section on the first is obtained when the first section is provided with an upstanding rib disposed substantially in line with the web portion and the second section is provided with a U-shaped rib surrounding the firstmentioned rib. Preferably the upstanding rib is of M-shaped section and the first section is fastened on the second section with the aid of a screw passing through the first section and fitting into the depression of the M-shaped rib.
This novel roof edging section has the advantage that leakage of water, which occurs in the known system along the web-like material under the influence of the wind is not possible and that the edge of the roof has an attractive exterior, the more because the second section can in principle be made from any suitable metal in any suitable color and shape (for instance eloxated extruded aluminum or stainless steel). Furthermore the system is easily removable, for instance, for inspection or other use.
Penetration of rain water until the front edge of the roof is minimal so that there are no vertical dirt stripes.
It is observed that a roof edging system with a removable cover strip is known in itself from the German Offenlegungsschrift No. 1.659.341. In this known structure the layer of roof covering is only covered by the removable strip which is made by a number of sections with spaces in between through which water can penetrate to behind the strip with all consequences thereof. Furthermore this structure uses complicated profiles which are difficult to mount.
From the German Offenlegungsschrift No. 1.609.913 is known a roof edging system with a pressure rib resting upon the layer of roof covering and thereabove a cover strip which covers this pressure rib only partially and carries screws acting upon the rib. Here, too, there are spaces between the various sections through which water can penetrate into the covering layers.
Finally the Dutch patent application No. 65.08538 describes a roof edging system in which mounting brackets carried by the roof support a profile with a part covering the front edge of the roof and a part lying above the roof with thereunder a clamping strip pressing upon the layers of roof covering. Removal of the profile has as result that the entire covering system falls apart so that it is not possible to mount this sytem in two phases or to remove the covering strip for inspection or exchange. Furthermore fitting the profile makes it necessary to act upon the screws which lie at a front edge of the building and are difficult to reach.